1. Field of the Invention
The present invention relates to a high frequency coil which is used as a noise suppressor in an ignition plug.
2. Description of the Prior Arts
One embodiment of the conventional high frequency coil is shown in FIG. 1 wherein windings (2) of bare wires are wound on a peripheral surface of a cylindrical ferrite magnetic core (1) in a space to form a coil and metallic cup-shaped electrode caps (3) are fitted at both ends of the ferrite magnetic core (1) and inner walls of the electrode caps (3) are respectively connected to both ends of the winding (2) wound on the ferrite magnetic core (1) to form an inductance device and a heat resistant electric insulating paint (4) is coated on the peripheral part of the inductance device between the electrode caps (3).
When the conventional high frequency coil is fitted by a spring (14) between a center electrode (12) and a terminal electrode (13) in a hollow insulator (11) of the ignition plug (10) shown in FIG. 2, a gap (g) between each electrode cap (3) and an inner wall of the hollow insulator (11) causes weak impact strength whereby it is not satisfactory in the impact strength test of Japanese Industrial Standard B-8031.